Globally, the number of orphans being adopted by foreign parents dropped from a high of 45,000 in 2004 to an estimated 25,000 last year, according to annual statistics compiled by Peter Selman, an expert on international adoptions at Britain's Newcastle University.
Some adoption advocates argue the decrease is also linked to a set of strict international guidelines known as the Hague Adoption Convention.
Devised to ensure transparency and child protection following a rash of baby-selling and kidnapping scandals, critics say the guidelines have also been used by leading adopting nations, including the US, as a pretext for freezing adoptions from some countries that are out of compliance.
''It should have been a real step forward, but it's been used in a way that's made it a force for shutting down'' adoptions in some countries, says Elizabeth Bartholet, a Harvard law professor who promotes international adoptions. ''That affects thousands of children every year.''
She says places where international adoptions are stopped may see more children in orphanages or on the street, where they could fall prey to sex traffickers.
US adoption officials and agencies such as UNICEF say the Hague rules, which require countries to set up a central adoption authority and a system of checks and balances, are necessary to safeguard orphans and keep profit-driven players from corrupting a system that should be purely about helping children.
Alison Dilworth, adoptions division chief at the US Office of Children's Issues and a supporter of the guidelines, says they shield adoptive parents from everyone's worst nightmare:
''God forbid, that knock on the door … saying your child that you have raised and loved and is fully integrated into your family was stolen from a birth parent who is desperately trying to look for them.''
Much has changed from a decade ago, when busloads of would-be foreign adoptive parents flocked to orphanages in China, Vietnam and Guatemala to take babies home following a relatively quick and easy process.
Waits have become longer and requirements stiffer, with some countries now refusing obese or single adoptive parents and requiring proof of a certain amount of cash in the bank. Countries embroiled in scandals have pulled the plug on their programs, or been cut off by the US and other countries, leaving hundreds of children in bureaucratic limbo.
Sharon Brooks, 56, of New York, knows the story all too well. She waited 3½ years for the release of a little girl in Vietnam after the US froze adoptions there in 2008 amid serious fraud concerns. In January, Ms Brooks learned the child she had named Akira-Li would instead be adopted by a Vietnamese family.
''That was my one shot,'' says Ms Brooks, who now believes she is too old to qualify for most international adoptions. ''Everything in my life has been at a standstill.''
Vietnam joined the Hague convention on February 1, and US officials say they are hopeful adoptions will resume within the next year.
Shutdowns in countries such as Guatemala, Nepal and Kyrgyzstan have coincided with efforts to promote domestic adoptions in countries such as Russia and China, where foreigners face tightened restrictions.
Advances in fertility treatments and the growing number of couples turning to surrogacy have also contributed to the drop.